1. Field of the Invention
The present invention relates to flexible polyurethane foams for use in cushioning materials and the like having improved physical properties. More particularly, the invention relates to polyurethane foam compositions containing junction modifying particulate additives.
2. Description of the Prior Art
Polyurethane foams are prepared by reacting, in the presence of a blowing agent, polyisocyanates with active hydrogen containing substances such as polyesters, including polyester amides, and hydroxyl containing polyethers including polyether diols and triols. Usually catalysts, such as organo-tin compounds and tertiary amines, and emulsifiers such as silicone oils are incorporated in the reaction mixture to control reaction rate, cell size and porosity.
The prior art has described many attempts to modify the properties of polyurethane foams by the addition of various inert filler materials. Typically these fillers were either organic or inorganic. In general, the prior art has taken two rather distinct approaches to the modification of flexible foams with fillers. In the more common approach, very finely divided particulate material is uniformly dispersed in the urethane precursor materials to achieve a modified product. See, e.g., Chandialia U.S. Pat. Nos. 4,278,770, Dwyer 3,441,253 and Marx 4,243,755. The art has also described the addition of very large particulate fillers to polyurethane foams. See, e.g., Knox U.S. Pat. No. 3,256,218. While the art also occasionally describes the use of intermediate size particulate additives, see, e.g., Hood U.S. Pat. No. 3,598,772 and U.K. Pat. No. 1,093,173, the prior art generally has not been able to provide a method for the consistent modification of various foam grades, densities and cell sizes. Accordingly, there has been no widespread commercial application of filled foams on anything other than a speciality product basis.
Clearly if various grades of polyurethane foams could be consistently formulated with relatively large amounts of filler material, these products would possess a significant economic advantage over unfilled structures comprised entirely of more expensive materials. This advantage would be even greater if such a modification also resulted in improved physical properties.
It is therefore an object of the present invention to provide a process for preparing modified polyurethane foams which enables the consistent production of products with excellent physical properties.
It is another object of the present invention to provide novel polyurethane foam products having excellent physical properties at substantially reduced costs.
It is also an object of the present invention to provide flexible polyurethane foam materials having a modulus of compression which is similar to that of rubber latex foam.
Another object of the present invention is to provide a modified polyurethane foam material having improved resilience characteristics so as to make it more suitable for use in furniture applications than prior art polyurethane foams.
It is also an object of the present invention to provide flexible polyurethane foam products which incorporate as a particulate property modifier recycled scrap organic polymeric materials.
It is a further object of the present invention to provide a process for producing a particulate modified flexible polyurethane foam product in a manner which does not cause accelerated wear of processing equipment.